igneous
Pegmatitic granite
Coarse-grained granite, chiefly quartz, feldspar, and mica; likely a granitic pegmatite
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale gray-white with pinkish feldspar and dark mica, exhibiting a coarse crystalline texture and glassy to pearly luster. Quartz has no cleavage, feldspar shows two cleavages, and mica commonly splits into sheets; specific gravity is approximately 2.6–2.7.
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Physical properties
Hardness about 6–7 Mohs; pale gray-white with pinkish feldspar and dark mica, exhibiting a coarse crystalline texture and glassy to pearly luster. Quartz has no cleavage, feldspar shows two cleavages, and mica commonly splits into sheets; specific gravity is approximately 2.6–2.7.
Formation & geological history
Forms when silica-rich magma cools slowly underground, allowing large interlocking crystals to grow; pegmatitic varieties form from late, water-rich residual magma. Its exact geological age cannot be determined from the image and may range from Precambrian to younger.
Uses & applications
Used as dimension stone, aggregate, countertops, and decorative material; attractive pieces are collected, though this specimen is not gem quality.
Geological facts
The visible large white, pink, gray, and black grains are characteristic of quartz, feldspar, and mica. Dark patches may include biotite or amphibole, while reddish areas are likely iron-stained feldspar.
Field identification & locations
Identify it by its coarse interlocking crystals, abundant pale feldspar, translucent gray quartz, and dark mica, without layering or foliation. Common in continental crust, granite outcrops, and pegmatite veins worldwide.
